Industrial sensors are commonly used in a wide variety of applications and environments. Industrial sensors, such as proximity, optical and photoelectric sensors, can be used to detect the presence or absence of targets on a conveyor belt. In addition, industrial sensors can be used to monitor various components of process machinery. Industrial sensors often use one or more light sources that serve as indicators to convey a status signal, such as power, output, or margin, to an end user during set-up and operation. Light from the light source is often conveyed through a light pipe or similar optical structure serving to guide the light to the external environment. The light source is often colored or projected through a colored lens to emit colored light, often green, yellow, orange, or red. The visibility of these light-guide-coupled light sources is often poor, particularly when viewed from a large off-center angle, such as when the sensor is mounted above a viewing angle of the end-user. With the light source typically mounted on a PCB inside the sensor enclosure, much of the light source's light intensity is either reflected, scattered, or absorbed before it makes its way to the external environment to be viewed. The result is that the sensor's indicator lights appear relatively dim and so for proper viewing an end-user may desire to move close to the sensor to view the indicators. Additionally, achieving a uniform illumination that is visible from all around the perimeter of the sensor is also problematic.
Furthermore, some industrial sensors, such as proximity sensors, often have a light source that is encapsulated in an epoxy potting material within the sensor housing. The light that is visible from the light source embedded in the potting is often faint as the majority of the light that is produced by the light source is either scattered or absorbed by the potting, preventing that light from escaping to the external environment where it can be viewed.
Various solutions have been tried to address poor sensor indicator visibility, such as selecting brighter (and possibly larger) light source components, increasing the electrical current supplied to the light source, and using physical optical structures such as prisms, light pipes, textured surfaces, polished surfaces, and facets. Although the aforementioned methods can increase indicator visibility, they include various drawbacks, such as more expensive parts, additional part processing, increased electric load on a base circuit, and increased housing size to accommodate larger parts or additional structures.
Therefore, it would be advantageous if an improved device or method for enhancing the visibility of sensor indicators could be developed that would allow one or more of the drawbacks discussed above and/or one or more other drawbacks to be entirely or at least partly overcome.